# Assesment of Hypoderma infestation in a wild population of Cervus elaphus from mountains Atlantic ecosystems in southwestern Europe (Spain)

## TL;DR

This study examines the infestation of red deer in Spain by Hypoderma warble flies, revealing high prevalence and seasonal patterns.

## Contribution

The study provides new insights into the chronobiology and distribution of Hypoderma actaeon in mountainous Atlantic ecosystems.

## Key findings

- A 42.7% prevalence of Hypoderma larvae was found in red deer with an aggregated distribution pattern.
- Larvae were detected in all three developmental stages, with seasonal variations in prevalence.
- Higher infestation rates were observed in adult males compared to young and females.

## Abstract

Hypodermosis in Cervus elaphus was studied in the Riaño Regional Hunting Reserve, Province of León, north-western Spain. One hundred and ten red deer were examined for the presence of warble fly larvae. They were analyzed by PCR analysis of the COI region of mt-DNA and identified as Hypoderma actaeon. The prevalence of larvae was 42.7% with a mean intensity of 12.5 ± 18 (range 1–80) warbles/deer infested. The distribution of larvae in the infested animals showed an aggregated/overdispersed pattern (aggregation index = 25.84), where the larvae are not randomly or uniformly distributed, but strongly aggregated among their hosts. Larvae were found in all three states. First and second-instars were observed mainly in the autumn until the end of winter (November-March) and third-instars in late winter until mid-spring (March–May). The adult animals and the males had a higher prevalence than the young and the females, finding statistically significant differences only according to the sex of the animals. Seasonal variations were observed in the prevalence with the highest number of infested animals in winter and autumn, but not in terms of the mean intensity of parasites. Additionally, we assessed the presence of anti-Hypoderma antibodies in serum by means of indirect ELISA tests, using a crude larval extract (CLE) and a purified fraction the hypodermin C (HyC) obtained from first instars of Spanish isolates of Hypoderma lineatum (cattle). These findings confirm that H. actaeon is widely distributed in northern Spain, and provide new information about its chronobiology in mountainous Atlantic ecosystems from southwestern Europe.